Shock isolation has generally been treated by simply providing a shock absorbing medium between elements in a structural system. Such "cushioning" can effectively prevent the transmission of vibration and shock from one structural element to another. However, the effectiveness of the isolation system is complicated by the necessity to fasten two structures together to prevent catastrophic failures. Further, each of the individual structures in such a system fully transmits the vibration and shock from one loading point to another on the structure.
The importance of protecting buildings from vibratory or impact dynamic motions resulting from seismic disturbances, wind vortices, reciprocating or unbalanced machines, or external impact such as fragment scattering has become increasingly important. The importance of seismic insulation particularly in the construction of nuclear power plants has become a matter of substantial investigation. For example, the isolation of building structures from seismic motion has been achieved by the prior art in some instances through the utilization of an elastomer such as rubber placed between plates (usually of steel) to form aseismic bearings. These bearings are placed beneath the building structure between the structure and its foundation. The seismic subsoil motion is thus isolated by the elastomers to greatly reduce the acceleration imparted to the building structure thus eliminating or minimizing damage and inhibiting the transmission of undesirable stresses and strains.
Typically, these prior art bearings are formed having multiple plates with intermediate elastomeric material thus forming a multi-layered structure. While such structures may be effective in the isolation of certain seismic disturbances, there nevertheless exists the necessity to counteract rocking motions by anchoring the building structure to the foundation. Such anchoring is required in the prior art apart from the aseismic bearing to prevent shear forces and/or uplift forces from disturbing the structural integrity of the building.